Heat exchangers are used in various capacities in automotive applications. For example, all automobiles having water cooled engines employ a radiator and a heater core. Automobiles equipped with air conditioning also include an evaporator and a condenser. These heat exchangers are made from aluminum and consist of two spaced header tanks interconnected by flow tubes having cooling fins extending therefrom. Fluid is circulated through the header tanks and flow tubes to effect the necessary temperature drop.
The header tanks, flow tubes, and cooling fins are rigidly attached to one another by brazing. It has been found that this brazing operation can be most efficiently accomplished in a furnace for mass production applications. The prior art teaches placing heat exchanger workparts on or suspending heat exchanger workparts from a continues container belt type flexible conveyor element for conveying the workparts through a brazing chamber in the furnace.
The conveyor element typically includes an upper, or support, straightaway for supporting and conveying the heat exchangers through the housing, and a return straightaway which is either passed inside or outside of the brazing chamber. When passed inside the brazing chamber, the return straightaway will be maintained at a substantially consistent temperature thereby not requiring reheating as it circulates back to the support straightaway. However, when circulated inside the brazing chamber, the return straightaway typically carries oxygen from the exterior atmosphere inside the braze furnace thereby contaminating the controlled atmosphere inside the braze furnace. Conversely, the return straightaway can be conveyed outside of the brazing chamber thereby eliminating the possibility of oxygen contamination in the controlled atmosphere in the braze furnace. Unfortunately, however, routing the return straightaway outside of the brazing chamber disputes a considerable amount of heat in the process.
Thus, additional heat energy must be supplied to the brazing chamber whenever the return straightaway is routed outside the brazing chamber, and oxygen contamination of the controlled atmosphere brazing chamber remains a problem wherein the return straightaway is routed inside the brazing chamber. Hence, the prior art fails to disclose a suitable method for maintaining the heat energy of the return straightaway of the conveyor element without contaminating the controlled atmosphere within the braze furnace.